Cascadia ADU: Your Full-Service Accessory Dwelling Unit Builder in the Pacific Northwest
Cascadia ADU, a division of Cascadia Design & Build LLC, is a premier ADU contractor serving homeowners across King, Snohomish, Skagit, and Chelan Counties in Washington State. With over 10 years of hands-on experience, they have established themselves as a trusted name in accessory dwelling unit design and construction, offering a comprehensive, end-to-end approach that covers everything from initial consultation to final completion.
What sets Cascadia ADU apart is their fully integrated in-house team, which includes design professionals, skilled builders, and an electrical crew. This means clients benefit from a streamlined process that is both faster and more cost-effective than working with multiple separate contractors. Their journey began with a single garage conversion more than a decade ago, and that foundational experience has shaped their deep commitment to quality craftsmanship and client satisfaction.
ADU Services Offered
Cascadia ADU provides a wide range of services tailored to meet the unique needs of each homeowner. Whether someone is looking to add a detached ADU to their backyard, convert an existing garage, or finish a basement into a livable space, their team has the expertise to deliver. Their core service offerings include:
- Attached ADUs – additions connected to the primary residence
- Detached ADUs – standalone backyard cottage or granny flat construction
- Garage Conversions – transforming existing garages into fully functional living spaces
- Basement Conversions – converting underutilized basement areas into comfortable ADUs
- New ADU Additions – custom-built units designed from the ground up
- À La Carte Services – individualized design or construction support at any stage of a project
Their in-house design team handles all drawing, planning, and permitting services, ensuring that every project complies with local zoning codes and regulations. They are well-versed in the permitting requirements across the counties they serve and can guide clients through the approval process efficiently. Many local jurisdictions now offer pre-approved ADU building plans, which Cascadia ADU leverages to reduce both planning costs and timelines.
Once permits are approved, construction moves quickly. Most projects are fully completed within 8 to 10 weeks, a testament to their organized workflow and experienced crew. They also incorporate sustainable and energy-efficient features into their builds, helping homeowners reduce their environmental footprint and long-term operating costs.
A Trusted ADU Contractor Built on Integrity and Local Expertise
Cascadia ADU operates with a mission-focused approach grounded in five core values: speed, quality, local expertise, integrity, and transparency. These principles guide every project they take on, from a modest in-law suite to a fully custom detached unit.
For homeowners who already have their own building plans, Cascadia ADU can work directly from those designs. For those starting from scratch, their design team will collaborate closely to develop a custom plan that aligns with the client's vision, budget, and goals. Three-dimensional renderings are also available, giving clients a realistic preview of their future ADU before construction begins.
Cascadia ADU also assists clients in navigating financing options, working with local community banks and lenders who specialize in ADU construction loans. Additionally, they can provide guidance on Washington State's updated ADU laws, including the possibility of "condoing" a completed ADU or DADU to sell it separately from the primary home.
Whether a homeowner is in the early research phase or ready to break ground, Cascadia ADU offers the flexibility and expertise to make the ADU journey as smooth and rewarding as possible.